Final answer:
Paul Baltes says that selection, also known as natural selection or 'survival of the fittest', mainly operates during the early stages of life. This is when evolutionary fitness is most critical, as organisms must quickly adapt to their environmental conditions to survive and reproduce, influencing the evolutionary trajectory of species.
Step-by-step explanation:
Paul Baltes indicated that selection, a key mechanism in the process of natural selection, primarily operates during the early stages of life. This idea underscores the principle that organisms with traits favorable to their environment are more likely to survive and produce offspring. Early on, the forces of natural selection are more evident, as this is the time when organisms must rapidly adapt to their surroundings to ensure survival and reproductive success.
It's in these initial phases of life where natural selection is most rigorous, as those who cannot adapt to the environmental demands quickly fall away from the gene pool. During this period, traits beneficial for survival and reproduction are swiftly distributed within a species, affecting the allele frequency in the gene pool and pushing evolutionary changes. The success of individuals in contributing to the next generation's gene pool is commonly referred to as evolutionary fitness.